SELinux defines process types (domains) for each process running on the system

You can see the context of a process using the -Z option to psbP

Policy governs the access confined processes have to files. SELinux postgrey policy is very flexible allowing users to setup their postgrey processes in as secure a method as possible.

The following process types are defined for postgrey:

postgrey_t

Note: semanage permissive -a postgrey_t can be used to make the process type postgrey_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated.

SELinux policy is customizable based on least access required. postgrey policy is extremely flexible and has several booleans that allow you to manipulate the policy and run postgrey with the tightest access possible.

If you want to allow all daemons to write corefiles to /, you must turn on the daemons_dump_core boolean. Disabled by default.

setsebool -P daemons_dump_core 1

If you want to enable cluster mode for daemons, you must turn on the daemons_enable_cluster_mode boolean. Enabled by default.

setsebool -P daemons_enable_cluster_mode 1

If you want to allow all daemons to use tcp wrappers, you must turn on the daemons_use_tcp_wrapper boolean. Disabled by default.

setsebool -P daemons_use_tcp_wrapper 1

If you want to allow all daemons the ability to read/write terminals, you must turn on the daemons_use_tty boolean. Disabled by default.

setsebool -P daemons_use_tty 1

If you want to deny any process from ptracing or debugging any other processes, you must turn on the deny_ptrace boolean. Enabled by default.

setsebool -P deny_ptrace 1

If you want to allow all domains to use other domains file descriptors, you must turn on the domain_fd_use boolean. Enabled by default.

setsebool -P domain_fd_use 1

If you want to allow all domains to have the kernel load modules, you must turn on the domain_kernel_load_modules boolean. Disabled by default.

setsebool -P domain_kernel_load_modules 1

If you want to allow all domains to execute in fips_mode, you must turn on the fips_mode boolean. Enabled by default.

setsebool -P fips_mode 1

If you want to enable reading of urandom for all domains, you must turn on the global_ssp boolean. Disabled by default.

setsebool -P global_ssp 1

If you want to allow system to run with NIS, you must turn on the nis_enabled boolean. Disabled by default.

The SELinux process type postgrey_t can manage files labeled with the following file types. The paths listed are the default paths for these file types. Note the processes UID still need to have DAC permissions.

SELinux requires files to have an extended attribute to define the file type.

You can see the context of a file using the -Z option to lsbP

Policy governs the access confined processes have to these files. SELinux postgrey policy is very flexible allowing users to setup their postgrey processes in as secure a method as possible.

EQUIVALENCE DIRECTORIES

postgrey policy stores data with multiple different file context types under the /var/run/postgrey directory. If you would like to store the data in a different directory you can use the semanage command to create an equivalence mapping. If you wanted to store this data under the /srv dirctory you would execute the following command:

SELinux defines the file context types for the postgrey, if you wanted to store files with these types in a diffent paths, you need to execute the semanage command to sepecify alternate labeling and then use restorecon to put the labels on disk.

- Set files with the postgrey_etc_t type, if you want to store postgrey files in the /etc directories.

postgrey_exec_t

- Set files with the postgrey_exec_t type, if you want to transition an executable to the postgrey_t domain.

postgrey_initrc_exec_t

- Set files with the postgrey_initrc_exec_t type, if you want to transition an executable to the postgrey_initrc_t domain.

postgrey_spool_t

- Set files with the postgrey_spool_t type, if you want to store the postgrey files under the /var/spool directory.

postgrey_var_lib_t

- Set files with the postgrey_var_lib_t type, if you want to store the postgrey files under the /var/lib directory.

postgrey_var_run_t

- Set files with the postgrey_var_run_t type, if you want to store the postgrey files under the /run or /var/run directory.

Paths:

/var/run/postgrey(/.*)?, /var/run/postgrey.pid

Note: File context can be temporarily modified with the chcon command. If you want to permanently change the file context you need to use the semanage fcontext command. This will modify the SELinux labeling database. You will need to use restorecon to apply the labels.